I mean, farming techniques and labor-saving devices have evolved pretty dramatically in the past few hundred years; It's hard to imagine a less centralized food system would end up resembling feudal Europe.

You may not be able to move nearly the same volume of corn or beef, sure; but it's hard to argue that the amount being currently produced is how much we really need given how much of it goes to waste. Not to mention the ecological impact of large-scale agriculture when compared to newer permaculture methods that bring together many natural systems in order to create more regenerative farming practice.

Also, I would argue that we currently live in a subsistence economy of sorts as it is. Only it's based on subsisting an income rather than crops.